The present invention relates generally to wireless communication systems and more particularly to synchronous two phase rate and power control in wireless local area networks (WLANs).
Wireless local area networks (WLANs) are becoming prevalent throughout the world. These networks offer users the convenience of being unteathered and free to move about. While initial growth was driven by the laptop community for the home market and home networking, a new market has quickly been emerging. Wireless designers have now incorporated WLAN technology into cell phones, PDA's and other mobile devices. Most of these mobile devices are battery powered, and end users expect at least a few days of continuous use between battery charges. In addition, the WLAN feature, which provides connectivity for the primary applications such as voice, should not significantly reduce the usage time for the primary applications.
One problem associated with a WLAN system is specifically related to mobile users. Mobile users who use dynamic power consumption often experience performance problems. These problems include undesirable data-rate adaptation, receiver-side interference and asymmetric channel access. Network designers are under the impression that dynamic transmit power control is a mismatch for voice over Internet protocol (VoIP) enabled WLANs and as such generally do not use adaptive power control in such systems. Other methods for managing WLANs have focused on either rate or power in isolation. One problem with these methods is that they do not address the problems of receiver-side interference and asymmetric channel access. In view of the foregoing observations, it is both desirable and advantageous to provide an effective method that can significantly reduce the effective power consumption of a WLAN mobile device.